Golf ball with velocity reduced layer

ABSTRACT

Disclosed herein is a golf ball comprising a core, a cover and a velocity-reduced layer disposed therebetween, wherein the velocity-reduced layer reduces the coefficient of restitution of the ball by at least 0.005, and wherein the velocity-reduced layer has a loss tangent in the range of 0.01 to 100 at frequency less than 100 Hz.

CROSS-REFERENCE TO RELATED APPLICATIONS

This non-provisional patent application is a continuation-in-part ofco-pending application entitled “Multi-layer Golf Ball” bearing Ser. No.10/194,291; a continuation-in-part of co-pending application entitled“Golf Ball Comprising a Plasticized Polyurethane” bearing Ser. No.10/741,987; a continuation-in-part of co-pending application entitled“Golf Ball with Vapor Barrier Layer and Method of Making Same” bearingSer. No. 10/755,638; and a continuation-in-part of co-pendingapplication entitled “Golf Ball with Vapor Barrier Layer and Method ofMaking Same” bearing Ser. No. 10/759,494. The disclosures of the parentcases are incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to golf balls, and more particularly, to agolf ball having a velocity-reduced layer.

BACKGROUND OF THE INVENTION

Golf balls can generally be divided into two classes: solid and wound.Solid golf balls include single-layer, dual-layer (i.e., solid core anda cover), and multi-layer (i.e., solid core of one or more layers and/ora cover of one or more layers) golf balls. Wound golf balls typicallyinclude a solid, hollow, or fluid-filled center, surrounded by tensionedelastomeric thread, and a cover. Solid balls have traditionally beenconsidered longer and more durable than wound balls, but lack theparticular “feel” that is provided by the wound construction andtypically preferred by accomplished golfers.

By altering ball construction and composition, manufacturers can vary awide range of playing characteristics, such as resilience, durability,spin, and “feel,” each of which can be optimized for various playingabilities. One golf ball component, in particular, that manymanufacturers are continually looking to improve is the center or core.The core is the “engine” that influences how far the golf ball willtravel when hit by a club head. Generally, golf ball cores and/orcenters are constructed with a polybutadiene-based polymer composition.Compositions of this type are constantly being altered in an effort toprovide a targeted or desired coefficient of restitution (“CoR”), whileat the same time often targeting a lower compression which, in turn, canlower the golf ball spin rate and/or provide better “feel.”

As recently reported in the press, due to the recent advances in golfball compositions and dimple designs, some of the high performance golfballs may eventually exceed the maximum distance of 317 yards±3yds, whenimpacted by a standard driver at 160 feet per second and at 10° angle asset forth by the United States Golf Association (USGA). (See “GolfBall's Historic Flight, New Product Is Hailed for Distance, Accuracy,”by L. Shapiro, The Washington Post at pp. D1, D4, Mar. 22, 2001). Asdisclosed in U.S. Pat. No. 5,209,485, to reduce the distance that a golfball would travel, inefficient dimple patterns and low resilientpolymeric compositions are suggested. Low resilient compositions includea blend of a commonly used diene rubber, such as high cis-polybutadiene,and a low resilient halogenated butyl rubber. Inefficient dimplepatterns include an octahedral pattern with a dimple free equator and adimple coverage of less than 50%. As disclosed in the '485 patent, theresulting ball travels about 50 yards less than comparative balls andhas a coefficient of restitution of about 0.200 less than thecoefficient of restitution of comparative balls. The '485 patenttheorizes that about 40% of the reduction in distance is attributable tothe inefficient design, and about 60% is attributable to the lowresilient ball composition. However, the art does not suggest a way tofine-tune the distance of high performance golf balls to adhere to theUSGA limit.

However, there remains a need in the art to fine tune the distance thata golf ball would travel without affecting the other desired qualities,such as resilience, durability, spin, and “feel” of the golf ball.

SUMMARY OF THE INVENTION

The present invention is directed to a high performance golf ball thathas a selectively reduced CoR with controlled weight, compression andspin rates.

Golf balls in accordance with the present invention comprise comprises acore, a cover and a velocity-reduced layer disposed therebetween,wherein the velocity-reduced layer reduces the coefficient ofrestitution of the ball by at least 0.005, and wherein thevelocity-reduced layer has a loss tangent in the range of 0.01 to 100 atfrequency less than 100 Hz.

DETAILED DESCRIPTION OF THE INVENTION

The distance that a golf ball would travel upon impact by a golf club isa function of the coefficient of restitution (CoR) and the aerodynamiccharacteristics of the ball, among other things. The CoR is defined asthe ratio of the relative velocity of two colliding objects after thecollision to the relative velocity of the two colliding objects prior tothe collision. For golf balls, the CoR has been approximated as a ratioof the velocity of the golf ball after impact to the velocity of thegolf ball prior to impact, and it varies from 0 to 1.0. A CoR value of1.0 is equivalent to a perfectly elastic collision, and a CoR value of0.0 is equivalent to a perfectly inelastic collision. The CoR is relatedto the initial velocity of the ball, which must not exceed 250±5 ft/s,which the maximum limit set forth by the USGA. Hence, the CoR of golfballs are maximized and controlled, so that the initial velocity of theball does not exceed the USGA limit.

The CoR of the golf ball is affected by a number of factors includingthe composition the core and the composition of the cover. The core maybe single layer core or multi-layer core. It may also be solid or fluidfilled. It may also be wound or foamed, or it may contain fillers. Onthe other hand, the cover may also be single layer cover or multi-layercover. The cover may be thin or thick. The cover may have a highhardness or low hardness to control the spin and feel of the ball. Thecover may comprise a thermoplastic or a thermoset material, or both.Compositions and dimensions of the cover and the core have been fullydiscussed in the four co-pending parent patent applications and also inthe art, such as U.S. Pat. Nos. 6,419,535, 6,152,834, 5,919,100,5,885,172, 5,783,293, 5,692,974, and PCT publication nos. WO 00/29129and WO 00/23519, among many others. Any of the above factors cancontribute to the CoR of the ball.

In accordance with one aspect of the present invention, the inventivegolf ball comprises a velocity-reduced layer, positioned preferablybetween the core and the cover. It may also be a part of the core or apart of the cover. Preferably, it is sized and dimensioned so that thereduction in CoR is incremental and selective. Additionally, it ispreferred that the velocity-reduced layer reduces the CoR of the ball byat least 0.005 less than the CoR of a golf ball without suchvelocity-reduced layer, when the volume of the velocity-reduced layerwould be occupied by the core.

A preferred material for the velocity-reduced layer is a visco-elasticpolymer. Visco-elastic polymer is a polymer that exhibits properties ofboth liquids, i.e., viscous flow, and solids, i.e., elasticity.Visco-elasticity depends on temperature, time duration or frequency ofthe applied force, e.g., shear forces or impact forces, and strain. Awell-known example of a visco-elastic material is Silly Putty® (see U.S.Pat. No. 2,541,851), which is a dimethyl silicone treated with acompound of boron and then heated. Silly Putty® behaves like an elasticsolid in reaction to a short-time stress, e.g., bouncing like a ball,and behaves like a viscous liquid in reaction to long-duration lowerstress, e.g., flowing like a liquid if left on a table top. Thesevisco-elastic properties also vary depending on the temperature of thepolymer.

Another desirable property of visco-elastic polymer is that it convertssome of the mechanical energy from the impact force to a small amount ofheat, thereby partially dissipating the energy that would otherwise beavailable to propel the golf ball. Hence, visco-elastic polymer is apreferred material in accordance with the present invention. Morepreferably, suitable visco-elastic polymers should exhibitvisco-elasticity in the range of ambient temperatures from about 40° F.to about 120° F.

An example of a suitable visco-elastic polymer is a thermoset,polyether-based, polyurethane material, commercially available asSorbothane® from Sorbothane, Inc., in Kent, Ohio. This thermosetpolyurethane is available with very low hardness, e.g., less than 20 ona Shore A durometer scale (or about 70 on Shore 00 scale), and morepreferably less than 40 Shore A. A typical characteristic of thismaterial is that it has low resilience in a rebound test, in accordancewith ASTM D2632 92 which has been modified to account for the tackinessof the polymer, and therefore would have a low CoR value whenincorporated on to a golf ball. Additionally, thermoplastic polyurethanealso exhibits visco-elasticity in the relevant temperature range, andtherefore is also suitable for the velocity-reduced layer. Polyurea,which has properties similar to polyurethane, is another suitablepolymer.

Generally the visco-elasticity is expressed as a damping coefficient,which indicates whether the material will bounce back or return theenergy to the system. For example, a visco-elastic polymer with a highdamping coefficient attenuates more of the force applied to it and has alow resilience. As stated above, the attenuated force is converted intoa small amount of heat. The damping coefficient can also be expressed asa loss tangent (tan δ), which is a dimensionless term and is a measureof the ratio of energy loss to energy stored in a cyclic deformation,i.e., tan δ=G″/G′. Higher value of the damping coefficient correspondsto higher absorption of the impact force for materials that are dampingin nature. Exemplary properties of a visco-elastic polymer, i.e.,Sorbothane® polyurethane, are listed below: Durometer Hardness 30 Shore00 (<5 50 Shore 00 (10-15 70 Shore 00 (20 Shore A) Shore A) Shore A)Resilience (Rebound Height Test) 16% 18% 25% ASTM D2632 92 Tangent ofDelta at 5 Hertz 0.30 0.56 0.56 Tangent of Delta at 15 Hertz 0.38 0.580.60 Tangent of Delta at 30 Hertz 0.45 0.57 0.59 Tangent of Delta at 50Hertz 0.35 0.50 0.55The loss tangent values are typically expressed at a particularfrequency, since a popular usage of visco-elastic polymer is to absorband attenuate vibration energy. In terms of its application to golf balldesign, the most applicable tangent of delta values would be the ones atthe lower frequency.

While there is no known direct correlation between the resilience of apolymeric compound, which is related to CoR, and its loss tangent, it isobserved that a material with a low resilience would typically have ahigh loss tangent or damping coefficient at a given frequency and %strain at a certain temperature value. Hence, polymeric compounds withlow resilience are also suitable for the velocity-reduced layer, some ofwhich may also have visco-elastic properties in the preferredtemperature range. Dynamic mechanical measurements on plastics can beconducted under ASTM D4092-89 and D4065-95 standards.

In accordance with one aspect of the present invention, thevelocity-reduced layer preferably comprises a visco-elastic materialwith a loss tangent value at room temperature (or in their segmentalmotion relaxation including its glass transition temperature) from about0.01 to about 100 at a frequency less than 100 Hz and at about 23° C.,and more preferably from about 0.05 to about 10 and most preferably fromabout 0.1 to about 10. In accordance with another aspect of theinvention, suitable materials for the velocity-reduced layer includepolymers with low resilience, such as those in the material CoR range ofabout 0.3 to about 0.7, and more preferably from about 0.4 to about 0.65and most preferably from about 0.45 to about 0.6. As used hereinmaterial CoR is the measured resilience or CoR of a solid sphere madefrom said material.

In accordance with another aspect of the present invention, thevelocity-reduced layer preferably comprises thermoplastic or thermosetresins that have a loss tangent at −20° C. from about 0.05 to 0.50.Suitable thermoplastic resins include, but are not limited to,polyamide, polyurethane, polyester, polyolefin, polystyrene and ionomerresins, and thermosetting resins include but are not limited to, epoxy,polyurethane, polyimide, polyurea and phenol resins. Two or more ofthese resins can be used in combination. Fillers, colorants,dispersants, anti-aging agents, high density fillers and other additivescan be added to the resins. Such resins are disclosed in U.S. Pat. No.6,843,734 B2 as outermost cover materials used to increase the ball'sspin rate. These materials or polymers are usable herein as a velocityreducing intermediate layer. The '734 patent is incorporated herein byreference in its entirety.

Other suitable materials for velocity-reduced layer include thosedisclosed in U.S. Pat. No. 6,578,836 B2, specifically from col. 2, line58 to col. 4, line 6. Additionally, materials used to dampen vibrationsin vehicles can also be used as the velocity-reducing layer. See, e.g.,U.S. Pat. No. 6,719,108 B2. The '836 and '108 patents are incorporatedherein in their entireties.

Exemplary suitable velocity reduced materials disclosed in the '836patent include diene type rubber and hydrogenated forms thereof such asNR, IR, epoxidated natural rubber, SBR, BR (high cis BR and low cis BR),acrylonitrile-butadiene rubber (NBR), hydrogenated NBR, hydrogenatedSBR; olefin type rubber such as ethylenepropylene rubber (EPDM, EPM),maleic acid modified ethylenepropylene rubber (M-EPM), butyl rubber(IIR), a copolymer of isobutylene and aromatic vinyl or diene typemonomer, acrylic rubber (ACM); halogen containing rubber such as Br-IIR,Cl-IIR, bromide of a isobutylene paramethyl styrene copolymer (Br-IPMS),chloroprene rubber (CR), hydrine rubber (CHR), chloro-sulfonatedpolyethylene (CSM), chlorinated polyethylene (CM), maleic acid modifiedchlorinated polyethylene (M-CM); silicone rubber such as methylvinylsilicone rubber, dimethyl silicone rubber, methylphenyl vinyl siliconerubber; sulfur containing rubber such as polysulfide rubber; fluorinerubber such as vinylidene fluoride type rubber, fluorine containingvinyl ether type rubber, tetrafluoroethylene-propylene type rubber,fluorine containing silicone type rubber, fluorine containingphosphazene type rubber; urethane rubber, epichlorohydrin rubber, andthe like. These rubber compositions may be composed of only one kind ora mixture of two or more kinds of these components. Further, an ordinaryvulcanizing agent or a cross-linking agent, a vulcanization acceleratoror a cross-linking accelerator, various kinds of oil, an antioxidant, afiller, a softener and various types of other compounding agentsgenerally mixed in the rubber can be mixed with the rubber composition.

Exemplary suitable thermoplastic resins include polyolefin type resin,polyamide type resin, polyester type resin, polyether type resin,polynitrile type resin, polymethacrylate type resin, polyvinyl typeresin, cellulose type resin, fluorine type resin, imide type resin, andthe like.

Suitable polyolefin resins include isotactic polypropylene, syndiotacticpolypropylene, ethylenepropylene copolymer resin, and the like. Suitablepolyamide resins include Nylon 6 (N6), Nylon 66 (N66), Nylon 46 (N46),Nylon 11 (N11), Nylon 12 (N12), Nylon 610 (N610), Nylon 612 (N612),Nylon 6/66 Copolymer (N6/66), Nylon Jun. 66, 19610 Copolymer(N6/66/610), Nylon MXD 6 (MXD 6), Nylon 6T, Nylon 6/6T Copolymer, Nylon66/PP Copolymer, Nylon 66/PPS Copolymer, a polyamide elastomer, and thelike. Suitable polyester resins include polybutylene terephthalate(PBT), polyethylene terephthalate (PET), polyethylene isophthalate(PEI), a polyester elastomer, a PET/PEI copolymer, polyarylate (PAR),polybutylene naphthalate (PBN), liquid crystal polyester, apolyoxy-alkylene diimide dioic acid/polybutylene terephthalatecopolymer, and the like. Suitable polyether resins include polyacetal(POM), polyphenylene oxide (PPO), polysulfone (PSF), polyether etherketone (PEEK), and the like. Suitable polynitrile resins includepolyacrylonitrile (PAN), polymethacrylonitrile, an acrylonitrile/styrenecopolymer (AS), a methacrylonitrile/styrene copolymer, amethacrylonitrile/styrene/butadiene copolymer, and the like. As specificexamples of the polymethacrylate resin, followings are enumerated:polymethyl methacrylate (PMMA), polyethyl methacrylate, and the like.Suitable polyvinyl resins include vinyl acetate (EVA), polyvinyl alcohol(PVA), a vinyl alcohol/ethylene copolymer (EVOH), polyvinylidenechloride (PVDC), polyvinyl chloride (PVC), a vinyl chloride/vinylidenechloride copolymer, a vinylidene chloride/methyl acrylate copolymer, andthe like. Suitable cellulose resins include cellulose acetate, celluloseacetate butyrate, and the like. Suitable fluorine resins includepolyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF),polychlorofluoroethylene (PCTFE), tetrafluoroethylene/ethylene copolymer(ETFE), and the like. Suitable imide resins include aromatic polyimide(PI) and the like.

In one embodiment, the velocity reduced layer is a rubbery, elastomericmaterial having a hardness from 10 Shore A to 50 Shore D, wherein theloss tangent at 23° C. is at least is less than 100, preferably lessthan 10 and more preferably less than 5. In another embodiment, thevelocity reduced layer is a thermoplastic rigid materials having ahardness range of 30 to 80 Shore D wherein the loss tangent at 23° C. atleast is less than 100, preferably less than 10 and most preferably lessthan 5.

In accordance with another aspect of the present invention, plasticizersare blended with polyurethane to provide higher flexibility, lowerhardness and lower rebound resulting in increased energy absorption.Specifically, the increased energy absorption property of plasticizedpolyurethane is particularly suitable for the velocity-reduced layer ofthe present invention. Plasticized polyurethane is fully disclosed incommonly owned U.S. Pat. No. 6,849,675, which is incorporated herein byreference in its entirety. Plasticized polyurethane is the combinationof polyurethane and plasticizer(s). Polyurethane is formed byconventional methods, such as forming a pre-polymer comprising a polyoland an isocyanate, followed by a curing agent. Plasticizer can be addedat a variety of points prior to, during, or after formation of theurethane or blends thereof. Plasticized polyurethane may bethermoplastic or thermosetting. Preferably, the amount of plasticizer inpolyurethane is about 1 to 30 parts per hundred parts of drypolyurethane weight (phr), and more preferably from about 5 phr to about25 phr.

The plasticizer is preferably selected from the group consisting ofalkyl adipates, alkyl phthalates, alkyl azelates, alkyl benzoates, alkylcitrates, soy and linseed oils, and mixtures thereof. The preferredplasticizer is dialkyl phthalate. Alternatively, the plasticizercomprises C₃-C₁₀ dialkyl adipates, C₃-C₁₀ dialkyl phthalates, or acetyltributyl citrate; or the plasticizer comprises dibutyl phthalate,bis(2-ethylhexyl) phthalate, diisopropyl adipate, dibutyl adipate,bis(2-ethylhexyl) adipate, acetyl tributyl citrate, or a mixturethereof.

In one embodiment, the plasticized polyurethane composition comprises afoamable polyurethane compound produced by the reaction of a polyol andtoluene diisocyanate, an amount of a non-halogen containing foamingagent sufficient to produce foam from the polyurethane compound, and anon-halogen containing plasticizer selected from the group consisting ofphthalate plasticizers and phosphate ester plasticizers. If theplasticized polyurethane is a non-halogen foaming agent, preferably thenon-halogen containing foaming agent is water or a non-halogencontaining gas. More preferably, the non-halogen containing foamingagent is water. Most preferably, the non-halogen containing plasticizeris a phosphate ester.

In another embodiment, the phosphate ester comprises 2-ethylhexyldiphenyl phosphate, isodecyl diphenyl phosphate, mixed dodecyl andtetradecyl diphenyl phosphate, trioctyl phosphate, tributyl phosphate,butylphenyl diphenyl phosphate, isopropylated triphenyl phosphate, or amixture thereof. Preferably, the phosphate ester comprises 2-ethyl hexyldiphenyl phosphate and isodecyl diphenyl phosphate. The phthalateplasticizer may comprise diisononyl phthalate, dihexyl phthalate,diheptyl phthalate, butyl octyl phthalate, linear dialkyl phthalatewherein the alkyl groups are independently carbon chains having fromseven to eleven carbon atoms, and butyl cyclohexyl phthalate.Alternatively, the non-halogen containing plasticizer is an alkyl arylphthalate.

In an alternative embodiment, the alkyl aryl phthalate comprises butylbenzyl phthalate, alkyl benzyl phthalate wherein said alkyl group has acarbon chain having from seven to nine carbon atoms, and texanol benzylphthalate. Ideally, the composition further comprises syntheticpolyisoprene, natural polyisoprene, polybutadiene, butyl rubber,polynorbornene, ethylene-propylene diene monomer rubber, orstyrene-butadiene rubber, combined with high levels of oils,plasticizers, fillers, and mixtures thereof.

The plasticizer may also comprise phthalic acid esters; aliphaticdibasic acid esters; trimellitate esters; fatty acid esters; benzoicesters; aliphatic phosphates; aromatic phosphates; halogenated aliphaticphosphates; and mixtures thereof. In a preferred embodiment, theplasticizer comprises a hydrophobic plasticizer. If so, the hydrophobicplasticizer comprises aromatic esters selected from the group consistingof dibutyl phthalate, dioctyl phthalate, diheptyl phthalate,bis(2-ethylhexyl) phthalate, dicyclohexyl phthalate, butyl laurylphthalate, diisooctyl phthalate, butylcoconutalkyl phthalate, ditridecylphthalate, dilauryl phthalate, diisodecyl phthalate, butylbenzylphthalate, octyldecanoyl phthalate, dimethylglycol phthalate,ethylphthalyl ethylene glycolate, methylphthalyl ethylene glycolate,butylphthalyl ethylene glycolate, dinonyl phthalate, diheptyl phthalate,octyldecyl phthalate, ditridecyl phthalate, dicapryl phthalate,bis(3,5,5-trimethylhexyl) phthalate, isooctylisodecyl phthalate,bis(diethyleneglycolmonomethylether) phthalate, and benzphenol.

Alternatively, the hydrophobic plasticizer may comprise aliphatic estersselected from the group consisting of mono-, di-, or polyester of higherfatty acid having 8 or more carbons with di-, tri-, or polyhydricalcohol, glycerin monostearate, glycerin 12-hydroxy stearate, glycerindistearate, diglycerin monostearate, tetraglycerin monostearate,glycerin monolaurate, diglycerin monolaurate, tetraglycerin monolaurate,polypropylene adipate, diisodecyl adipate, bis(2-methylhexyl) adipate,dicapryl adipate, diisooctyl adipate, octyldecyl adipate,isooctylisodecyl adipate, dibutyl fumarate, dioctylfumarate, triethylcitrate, acetyltriethyl citrate, tributyl citrate, and acetyltributylcitrate.

Still alternatively, the hydrophobic plasticizer may comprise phosphateesters selected from the group consisting of tricresyl phosphate,phenyldicresyl phosphate, xylenyldicresyl phosphate, cresyldixylenylphosphate, triphenyl phosphate, tributyl phosphate, trichloroethylphosphate, trioctyl phosphate, tributyl phosphate, trichloroethylphosphate, trioctyl phosphate, triethyl phosphate, and arylalylphosphate. The hydrophobic plasticizer may also include epoxy compoundsselected from the group consisting of butylepoxy stearate, octylepoxystearate, epoxybutyl oleate, epoxidized butyl oleate, epoxidized soybeanoil, epoxidized linseed oil, epoxidized alkyl oil, and epoxidized alkyloil alcohol ester; and mixtures thereof.

In still another embodiment, the plasticizer is selected from the groupconsisting of alkyl adipates, alkyl phthalates, alkyl azelates, alkylbenzoates, alkyl citrates, similar soy and linseed oils, C₃-C₁₀ dialkyladipates, C₃-C₁₀ dialkyl phthalates, acetyl tributyl citrate, dibutylphthalate, bis(2-ethylhexyl) phthalate, diisopropyl adipate, dibutyladipate, bis(2-ethylhexyl) adipate, acetyl tributyl citrate, phthalates,adipates, sebacates, azelates, trimellitates, glutarates, benzoates,alkyl alcohols, phosphates, and mixtures thereof.

In accordance with another aspect of the invention, suitable polymersfor the velocity-reduced layer include the latex disclosed in U.S.application publication no. 2001/0005699, which is been incorporated byreference. The disclosed polymers include elastomer latex thatpreferably has a flexural modulus of less than 10,000 psi and morepreferably less than 3,000 psi. A preferred elastomer latex is athermosetting latex, such as low ammonia natural latex, pre-vulcanizednatural latex, elastomer adhesives, synthetic latexes, acrylic esters,alkyd resins, or mixtures there of. Latex possesses high tensilestrength, good elasticity, low flexural modulus and a strong ability toform strong, coherent films or thin layers. Using the preferred latex,the velocity-reduced layer can be as thin as about 0.0005 inch to about0.01 inch. The hardness of such layer is typically less than 90 Shore Aor less. Such layer absorbs some of the impact force from the club andthereby reducing the force propelling the ball. This reference alsodiscloses other suitable visco-elastic polymers, which may be solid,semi-solid, gel, or gel like, and exhibit changing viscosity in responseto shear forces, tensile forces and/or compressive strain. The disclosedvisco-elastic polymers include polydimethyl siloxane, dimethylcyclosiloxane, hydroxy-terminated polydimethyl siloxane, uncuredpolybutadiene, polybutadiene lightly cured with low levels of peroxide,zinc oxide and less than 10 phr of zinc diacrylate or anotherα,β-unsaturated carboxylic acid, polyvinyl alcohol, acrylic-plastisol,acrylic organosol, hydrocarbon based gel, sulfonated ionomer, butylrubber ionomer, ionized cross-linked polyacrylamide gel, microporousfast-response gel, thermoelastomer elastomer gel, or blends thereof.Additionally, ionomers, metallocene polymers, polycarbonate/polyesterblends, polyvinylidene fluoride (PVDF) such as Kynar®, fluoroelastomersuch as Viton®, thermoplastic urethane including silicone-urethane andurea can be incorporated into the latex.

In accordance with another aspect of the invention, suitable polymersfor the velocity-reduced layer include polysulfide rubber disclosed inU.S. application publication no. 2003/0069082, which is incorporated byreference. Polysulfide rubber dissipates the impact energy from the golfclub to attenuate the rebound energy available for ball propulsion.Polysulfide rubber typically is available in three forms: (i) amillable, extrudable solid elastomer that exhibits thermoplasticproperties, (ii) a dispersion of high molecular weight polymer insolvents, or (iii) a liquid polymer.

The chemical compositions and the reactions necessary to producepolysulfide rubber are well known and are fully described in U.S. Pat.Nos. 2,195,380, 2,466,963 and 3,243,403 among others. The disclosures ofthese patents are incorporated herein by reference in their entireties.In general, polysulfide rubbers are synthetic polymers prepared byreacting polyfunctional organic compounds with alkali metal or alkalineearth metal sulfide solutions to provide high molecular weight polymershaving the recurring unit, RSS, wherein R is typically a divalentorganic radical and SS is a disulfide linkage through which the organicradicals are interconnected. To improve the properties of thepolysulfide polymers, a mixture of difunctional and trifunctionalorganic compounds is typically used. The trifunctional compound ispresent at a relatively small amount to produce a slightly cross-linkedstructure. The organic radicals typically include aliphatic halides,e.g., alkylene chlorides, such as ethylene dichloride and itshomologues, or oxygen-containing aliphatic dichloride such asbis-beta-chloroethyl ether and bio-beta-chloroethyl formal.

Examples of suitable liquid polysulfide rubbers include those preparedfrom bis-beta-chloroethyl formal and are essentially composed ofrecurring (S.CH₂.CH₂.O.CH₂.O.CH₂.CH₂.S) groups and have free mercaptoterminals through which the liquid may be cured. Typically, a smallpercentage of trichloropropane is mixed with the bis-beta-chloroethylformal to provide the cross-linking. Suitable curing agents include anoxidizing agent such as zinc peroxide, lead peroxide or the curingagents disclosed in the '963 patent. Other non-toxic curing agents aredisclosed in U.S. Pat. No. 3,046,248, which is incorporated herein byreference. Modifying agents, such as cure-retarding agents, cureaccelerating agents, pigments, fillers may be incorporated into thecomposition. By selecting the proper curing agents and modifying agents,cures at room temperature can be achieved. On the other hand, cures atelevated temperature can be used to reduce the overall curing time.Cures may also be accelerated in the presence of acid, and retardedunder alkaline conditions, when dibutyl tin oxide is used as a curingagent. On the other hand, when other curing agents are used, cures maybe retarded under acidic conditions and accelerated under alkalineconditions. Typically, the liquid base polymer and the curing agent(s)are mixed just prior to use. It is also possible to premix the liquidbase polymer and the curing agent(s) under anhydrous conditions, andimmediately before use water is added to the premixed condition to curethe polymer.

Liquid polysulfide polymers are also available in a single component ora one-part stable, hygroscopic liquid polymer that cures when itcontacts moisture in atmospheric air without the need of curing agent(s)or water. Examples of such one-part liquid polymer include a liquidpolyalkylene polysulfide polymer. Dispersed in such liquid are a dormantcuring agent that is activated by the presence of moisture, and awater-soluble deliquescent accelerating agent adapted to attract andabsorb moisture from the surrounding. Such one-part curable polymer isdisclosed in U.S. Pat. No. 3,225,017, and the disclosure of this patentis hereby incorporated by reference in its entirety. The one-partcurable polymer may be initially dried to remove moisture.Alternatively, the deliquescent accelerating agent may also be adesiccating agent to dry the polymer. Alternatively, a single additivecan be desiccating, deliquescent, dormant curing and accelerating agentdispersed to dry the polymer and to cure the polymer when exposed tomoisture. Suitable curing agents for the one-part curable polymersinclude organic oxidizing agents, such as dinitro benzene, and inorganicoxides, such as alkali metal and alkali metal salt peroxide (e.g.,sodium peroxide, sodium pyrophosphate peroxide, sodium carbonateperoxide and sodium perborate), the alkali earth metal peroxides (e.g.,calcium peroxide and barium peroxide), and other metal peroxides such aszinc peroxide and manganese dioxide and oxidizing agents (e.g. ammoniumdichromate).

Another example of a curable liquid polysulfide polymer at roomtemperature by atmospheric moisture with or without additional curingagents or catalysts is an isocyanate-terminated polysulfide polymer,disclosed in U.S. Pat. No. 3,386,963. Another example of anisocyanate-terminated liquid polysulfide polymer is disclosed in U.S.Pat. No. 6,322,650 B1. Another example of a liquid polysulfide polymercurable at room temperature relatively quickly (less than 1 hour atabout 70-75° F.) is disclosed in U.S. Pat. No. 3,637,574. Thesereferences are incorporated herein by reference.

In the solid form, polysulfide rubber is a cured or vulcanized rubbercapable of flow under pressure and elevated temperature with substantialrecovery of its preflow physical properties upon cooling. As the solidpolymer is heated to a flowable state, the polysulfide rubber can beextruded or it can be cast into a mold to form a layer for the golfball.

Examples of solid, extrudable and castable polysulfide rubbers aredisclosed in U.S. Pat. Nos. 4,263,078, 4,165,425 and 4,190,625 amongothers. The '625 patent discloses a thermoplastic, elastomericpolysulfide rubber that can be extruded or cast. This polysulfide rubberis a hydroxyl terminated rubber cured by a zinc oxide. It also hassulfur linkages averaging about at least 1.8 sulfur atoms per linkageunit and is catalyzed by an alkali metal hydroxide. The catalytic agentinduces softening on heating and helps the elastomer to regain itspre-heating properties upon cooling. The extrusion of this polysulfiderubber is accomplished using standard equipment suitable for extrudingother solid thermoplastic elastomers.

In another example, the solid polysulfide rubber is cured with loweralkyl tin oxide, such as di-n-butyl tin oxide, and used in hot appliedprocesses as disclosed in the '425 patent. This particular polysulfiderubber is thiol terminated and cured with the lower alkyl tin oxide attemperatures between 100° C. and 300° C. to become a solid thermoplasticelastomer that can be softened by heating and then cast or injectionmolded into a velocity-reduced layer.

Another suitable solid polysulfide rubber is based on a thiol terminatedliquid polysulfide polymer cured with zinc oxide and a sulfur containingcompound selected from 2-mercaptobenzothiazol, zinc lower alkyldithiocarbamate and alkyl thiuram polysulfides at temperatures fromabout 200° F. to about 390° F. Agents, which improve the flowingproperties of the composition, such as copolymers of styrene andalkylenes, organic or inorganic reinforcing fibrous materials, phenolicresins, coumarone-indene resins, antioxidants, heat stabilizers,polyalkylene polymers, factice, terpene resins, terpene resins esters,benzothiazyl disulfide or diphenyl guanidine, can also be added to thecomposition. Advantageously, this polysulfide rubber possesses a goodability to wet the substrate and forms good bonds with such substratewhen cooled.

Polysulfide rubber is also available dissolved in a solvent, such asaliphatic and aromatic hydrocarbons, esters, ketones and alcohols, amongothers. Solvents are typically used to reduce the viscosity of liquidpolysulfide to apply the polysulfide as a thin film of velocity-reducedlayer on the golf ball. The solvent is allowed to evaporate or otherwiseflashed before the cover is encased on the core sub-assembly. Theadvantages of a solvent-based polysulfide rubber are thatvelocity-reduced layer can be formed by dipping or spraying and that noprecise mixing of the multiple components is required.

In accordance with another aspect of the invention, suitable polymersfor the velocity-reduced layer include butyl rubber disclosed in U.S.application publication no. 2003/0069085, which is incorporated hereinby reference. Butyl rubber is another preferred material with an abilityto dissipate the impact energy from golf clubs to attenuate the reboundenergy available for ball propulsion. For instance, the resilience ofbutyl rubber as measured on a Bashore resiliometer is in the range of18% to 25%, as compared to cis-polybutadiene rubber, which is in therange of 85%-90% when they are cross-linked using appropriatecross-linking agents Butyl rubber (IIR) is an elastomeric copolymer ofisobutylene and isoprene. Detailed discussions of butyl rubber areprovided in U.S. Pat. Nos. 3,642,728, 2,356,128 and 3,099,644. Thedisclosures of these references are incorporated herein by reference intheir entireties. Butyl rubber is an amorphous, non-polar polymer withgood oxidative and thermal stability, good permanent flexibility andhigh moisture and gas resistance. Generally, butyl rubber includescopolymers of about 70% to 99.5% by weight of an isoolefin, which hasabout 4 to 7 carbon atoms, e.g., isobutylene, and about 0.5% to 30% byweight of a conjugated multiolefin, which has about 4 to 14 carbonatoms, e.g., isoprene. The resulting copolymer contains about 85% toabout 99.8% by weight of combined isoolefin and 0.2% to 15% of combinedmultiolefin. Commercially available butyl rubbers, such as thosemanufactured by ExxonMobil Chemical Company, typically have about 1 to2.5 mole percent of isoprene. Butyl rubbers generally have molecularweight of about 20,000 to about 500,000. Suitable butyl rubber is alsoavailable from United Coatings under the tradename Elastron™ 858.Elastrom 858 is a butyl rubber coating applied as a solution in avolatile hydrocarbon solvent, which is typically sprayed or dipped on toan object or a surface, and contains lead peroxide as a crosslinkingagent.

Butyl rubbers are also available in halogenated form. Halogenated butylrubbers may be prepared by halogenating butyl rubber in a solutioncontaining inert C3-C5 hydrocarbon solvent, such as pentane, hexane orheptane, and contacting this solution with a halogen gas for apredetermined amount of time, whereby halogenated butyl rubber and ahydrogen halide are formed. The halogenated butyl rubber copolymer maycontain up to one halogen atom per double bond. Halogenated butylrubbers or halobutyl rubbers include bromobutyl rubber, which maycontain up to 3% reactive bromine, and chlorobutyl rubber, which maycontain up to 3% reactive chlorine. Halogenated butyl rubbers are alsoavailable from ExxonMobil Chemical.

Butyl rubber is also available in sulfonated form, such as thosedisclosed in the '728 patent and in U.S. Pat. No. 4,229,337. Generally,butyl rubber having a viscosity average molecular weight in the range ofabout 5,000 to 85,000 and a mole percent unsaturation of about 3% toabout 4% may be sulfonated with a sulfonating agent comprising a sulfurtrioxide (SO₃) donor in combination with a Lewis base containing oxygen,nitrogen or phosphorus. The Lewis base serves as a complexing agent forthe SO₃ donor. SO₃ donor includes compound containing available SO₃,such as chlorosulfonic acid, fluorosulfonic acid, sulfuric acid andoleum.

Other suitable velocity-reduced polymers include the elastomers thatcombine butyl rubbers with the environmental and aging resistance ofethylene propylene diene monomer rubbers (EPDM), commercially availableas Exxpro™ from ExxonMobil Chemical. More specifically, these elastomersare brominated polymers derived from a copolymer of isobutylene (IB) andp-methylstyrene (PMS). Bromination selectively occurs on the PMS methylgroup to provide a reactive benzylic bromine functionality. Anothersuitable velocity-reduced polymer is copolymer of isobulyline andisoprene with a styrene block copolymer branching agent to improvemanufacturing processability.

Another suitable polymer is polyisobutylene. Polyisobutylne is ahomopolymer, which is produced by cationic polymerization methods.Commercially available grades of polyisobutylene, under the tradenameVistanex™ also from ExxonMobil Chemical, are highly paraffinichydrocarbon polymers composed on long straight chain moleculescontaining only chain-end olefinic bonds. An advantage of such elastomeris the combination of low rebound energy and chemical inertness toresist chemical or oxidative attacks. Polyisobutylene is available as aviscous liquid or semi-solids, and can be dissolved in certainhydrocarbon solvents.

Halogenated butyl rubber can be blended with a second rubber, preferablya double bond-vulcanizable rubber, in a specific mixing ratio in atwo-step kneading process and then cured to form a rubber blend that hashigh adhesion to diene rubbers. This rubber blend is discussed in U.S.Pat. No. 6,342,567 B2. The '567 patent is hereby incorporated herein byreference. Alternatively, a brominated isobutylene/p-methylstyrene,discussed above, can be used in place of the halogenated rubber. Othersuitable polymers include thermoplastic elastomer blends that may bedynamically vulcanized and comprise a butyl rubber or a halogenatedbutyl rubber, such as those discussed in U.S. Pat. Nos. 6,062,283,6,334,919 B1 and 6,346,571 B1. These references are incorporated hereinby reference. Alternatively, butyl rubber may be blended with avinylidene chloride polymer, i.e., saran, as disclosed in U.S. Pat. No.4,239,799. The '799 patent is also incorporated herein by reference.

Butyl rubbers can be cured by a number of curing agents. Preferredcuring agents for golf ball usage include sulphur for butyl rubber, anda peroxide curing agent, preferably zinc oxide, for halogenated butylrubbers. Other suitable curing agents may include antimony oxide, leadoxide or lead peroxide. Lead based curing agents may be used whenappropriate safety precautions are implemented. Butyl rubbers arecommercially available in various grades from viscous liquid to solidswith varying the degree of unsaturation and molecular weights.

Butyl rubber and halogenated butyl rubber can be processed by milling,calendering, extruding, injection molding and compression molding, amongother techniques. These processing techniques can produce a semi-curedsheets or half-shelves of the velocity-reduced polymer, which can bewrapped around a core or a core subassembly. The velocity-reduced layercan be fully cured by exposure to heat at elevated temperaturestypically in the range of about 250° F. to 450° F.

In accordance with another aspect of the invention, another suitablevelocity-reduced polymer is poly(vinyl chloride) or PVC. Poly(vinylchloride) is a vinyl polymer and produced by polymerizing vinylchloride. Additionally, any number of fillers, additives, fibers andflakes, such as mica, micaceous ion oxide, metal, ceramic, graphite,aluminum or more preferably leafing aluminum, can be incorporated intothe velocity-reduced layer. Alternatively, the velocity-reduced layermay comprise a foamed polymer, such as the foamed plasticizedpolyurethane, discussed above.

In a preferred embodiment, a golf ball in accordance with the presentinvention has a diameter of about 1.68 inches and weighs about 1.62ounces. The ball comprises a core and a cover with a velocity-reducedlayer disposed therebetween. The velocity-reduced layer comprises any ofthe suitable polymers described above, or a blend thereof, and has athickness of at least 0.003 inch (or less if latex is used, as discussedabove), and preferably from about 0.003 inch to about 0.040 inch, morepreferably from about 0.005 inch to about 0.030 inch and most preferablyfrom about 0.005 inch to about 0.020 inch.

For example, a golf ball with a single-layer solid core of 1.59 inch indiameter and made from a conventional high resilience core of highcis-polybutadiene rubber with ZDA reactive co-agent and peroxidecross-linking agent with a single layer ionomer cover has a compressionof about 90 and a CoR of about 0.810. When a velocity-reduced layer ofabout 0.020 inch thick made from the suitable polymers disclosed hereinis incorporated between the core and the cover, and the core is reducedto about 1.55 inch, the resulting CoR is no greater than 0.805 andpreferably no greater than 0.800.

The velocity-reduced layer may have any hardness, but preferably has adurometer measurements from about 5 on Shore C scale to about 80 onShore D scale, more preferably from about 10 Shore C to about 95 ShoreC. The golf ball in accordance with the invention has CoR in the rangefrom about 0.500 to about 0.845, more preferably from about 0.600 toabout 0.825 and most preferably from about 0.650 to about 0.810.

In the case of ionomers, the loss tangent at 23 deg. C. is less than 1,preferably less than 0.1, and more preferably in the range of 0.01 to0.09. In the case of rigid thermoplastic materials, the loss tangent at23 deg. C. is less than 1, preferably less than 0.1 and more preferablyin the range of 0.01 to 0.09.

Hardness is preferably measured pursuant to ASTM D-2240 in either buttonor slab form on the Shore D scale. More specifically, Shore D scalemeasures the indentation hardness of a polymer. The higher Shore D valueindicates higher hardness of the polymer. Compression is measured byapplying a spring-loaded force to the golf ball center, golf ball coreor the golf ball to be examined, with a manual instrument (an “Attigauge”) manufactured by the Atti Engineering Company of Union City, N.J.This machine, equipped with a Federal Dial Gauge, Model D81-C, employs acalibrated spring under a known load. The sphere to be tested is forceda distance of 0.2 inch (5 mm) against this spring. If the spring, inturn, compresses 0.2 inch, the compression is rated at 100; if thespring compresses 0.1 inch, the compression value is rated as 0. Thusmore compressible, softer materials will have lower Atti gauge valuesthan harder, less compressible materials. Compression measured with thisinstrument is also referred to as PGA compression. The approximaterelationship that exists between Atti or PGA compression and Riehlecompression can be expressed as:(Atti or PGA compression)=(160−Riehle Compression).

According to other aspects of the present invention, the velocityreduced materials discussed above can be used in the core and/or thecover, either alone or in combination with other polymers. Also, morethan one velocity reduced layers can be provided on a single ball.Furthermore, the velocity reduced layer(s) can be castable ornon-castable, thermoplastic or thermoset.

Other than in the operating examples, or unless otherwise expresslyspecified, all of the numerical ranges, amounts, values and percentagessuch as those for amounts of materials and others in the specificationmay be read as if prefaced by the word “about” even though the term“about” may not expressly appear with the value, amount or range.Accordingly, unless indicated to the contrary, the numerical parametersset forth in the specification and attached claims are approximationsthat may vary depending upon the desired properties sought to beobtained by the present invention. At the very least, and not as anattempt to limit the application of the doctrine of equivalents to thescope of the claims, each numerical parameter should at least beconstrued in light of the number of reported significant digits and byapplying ordinary rounding techniques.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contain certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Furthermore, when numerical ranges ofvarying scope are set forth herein, it is contemplated that anycombination of these values inclusive of the recited values may be used.

While various descriptions of the present invention are described above,it is understood that the various features of the embodiments of thepresent invention shown herein can be used singly or in combinationthereof. For example, the dimple depth may be the same for all thedimples. Alternatively, the dimple depth may vary throughout the golfball. The dimple depth may also be shallow to raise the trajectory ofthe ball's flight, or deep to lower the ball's trajectory. Thisinvention is also not to be limited to the specifically preferredembodiments depicted therein.

1. A golf ball comprising a core, a cover and a velocity-reduced layerdisposed therebetween, wherein the velocity-reduced layer reduces thecoefficient of restitution of the ball by at least 0.005, and whereinthe velocity-reduced layer has a loss tangent in the range of 0.01 to100 at frequency of about 100 Hz.
 2. The golf ball of claim 1, whereinthe velocity-reduced layer comprises a polyurethane or polyurea having amaterial hardness of less than 40 Shore A.
 3. The golf ball of claim 1,wherein the velocity-reduced layer comprises a polyurethane or polyureahaving a material hardness less than about 20 Shore A.
 4. The golf ballof claim 1, wherein the loss tangent is in the range of 0.05 to
 50. 5.The golf ball of claim 4, wherein the loss tangent is in the range of0.1 to
 10. 6. The golf ball of claim 1, wherein the velocity-reducedlayer has a material coefficient of restitution of 0.3 to 0.7.
 7. Thegolf ball of claim 6, wherein the material coefficient of restitution isin the range of 0.4 to 0.65.
 8. The golf ball of claim 7, wherein thematerial coefficient of restitution is in the range of 0.45 to 0.6. 9.The golf ball of claim 1, wherein the velocity-reduced layer comprisesplasticized polyurethane.
 10. The golf ball of claim 9, wherein theplasticized polyurethane is foamable.
 11. The golf ball of claim 1,wherein the velocity-reduced layer comprises latex.
 12. The golf ball ofclaim 11, wherein the latex has a flexural modulus of less that 10,000psi.
 13. The golf ball of claim 12, wherein the latex has a flexuralmodulus of less than 3,000 psi.
 14. The golf ball of claim 11, whereinthe latex has a material hardness of less than 90 Shore A.
 15. A golfball comprising a core, a cover and a velocity-reduced layer disposedtherebetween, wherein the velocity-reduced layer reduces the coefficientof restitution of the ball by at least 0.005, and wherein thevelocity-reduced layer comprises a rubbery elastomeric material having ahardness from 10 Shore A to 50 Shore D wherein the loss tangent at 23°C. and a frequency of about 100 Hz is less than
 100. 16. The golf ballof claim 15 wherein the loss tangent is less than
 10. 17. The golf ballof claim 15, wherein the loss tangent is less than
 5. 18. A golf ballcomprising a core, a cover and a velocity-reduced layer disposedtherebetween, wherein the velocity-reduced layer reduces the coefficientof restitution of the ball by at least 0.005, and wherein thevelocity-reduced layer comprises a thermoplastic rigid materials havinga hardness from 30 to 80 Shore D, wherein the loss tangent at 23° C. anda frequency of about 100 Hz is less than
 100. 19. The golf ball of claim18, wherein the loss tangent is less than
 10. 20. The golf ball of claim18, wherein the loss tangent is less than 5.